Method of and apparatus for preheating vitrifiable batch



United States Patent 475,809 s claims. (c1. 263-30) The present invention relates to a method of and apparatus for the preheating of vitriiiable batch during introduction into glass furnaces, and concerns more especially furnaces in which the material is heated in the course of its descent through a current of hot fumes coming from the melting zone.

In known glass furnaces, the fumes leave the furnace at a very high temperature and their sensible heat is generally recovered in recuperators, which have the disadvantage of being very bulky and very costly, while recovering only a part of the utilizable heat contained in the fumes leaving the furnace. In order to obviate these disadvantages, it has been proposed to recover the heat contained in the fumes by heating the vitrifiable batch by means of the fumes. In apparatus of this type, the vitriiiable composition circulates in counter-current relationship to the hot fumes leaving the melting zone of the furnace and becomes heated while cooling the fumes.

The invention has for its object to improve the thermal yield of such apparatus.

To this end, there is provided in the path of the fumes a large development of surfaces which are heated by the fumes and retransmit their heat by radiation to the batch. By this means, the quantity of heat transferred from the fumes to the batch for a given furnace volume is increased. The fumes give up their heat to the batch and simultaneously to the radiating surfaces which radiate the heat received to the batch and thus increase the quantity of heat recovered by the batch.

Preferably, the current of hot fumes leaving the melting zone is divided into a number of partial currents passing between separate radiating surfaces. As a result of the subdivision of the gas current, a more complete contact is ensured between each gas current and the radiating surfaces, and the fumes are caused to ow between the large surfaces absorbing an appreciable quantity of their sensible heat.

The vitriiiable batch is advantageously distributed between the various partial currents of fumes in accordance with the rate of flow of the latter. By proportioning the rate of supply of materials to the rate of flow of hot fumes, an optimum transfer of heat to the solid materials is ensured.

In accordance with the invention, an apparatus in which the vitriiable batch is preheated by counter-current circulation of hot fumse emanating from the melting Zone comprises in the path of the fumes elements having a large development of surfaces which are heated by the fumes and radiate towards the grains of vitriable batch. These elements may consist of ceramic material, more particularly of a ceraniic-metal mixture known under the name cermet. They are advantageously made of metal, for example sheet metal, and formed of tubes or chains. By this means, the surface through which the heat of the fumes is extracted is no longer limited to the surface of "ice the grains, but is increased by the large surface of the elements contained in the interior of the furnace. These elements continuously give up by radiation to the grains the heat received from the fumes.

In accordance with an advantageous embodiment, the elements of large surface contained in the interior of the furnace are so disposed as to form a number of compartments open at both ends, what is to say, in the direction of travel of the fumes, which compartments may be separated from one another. By this arrangement, the current of fumes is divided into a number of partial currents which are more intimately brought into contact with the various exchange surfaces than a single current, in which preferential currents which are badly distributed over the cross-section of the furnace may be setup.

The apparatus also comprises a device for the distribution of the vitrifiable batch, so that the latter is distributed among various compartments in accordance with a chosen law.

For example, a screen is employed in which the apertures are uniformly distributed over its entire surface. However, the supply of batch to each compartment is advantageously controlled in proportion with the rate of iiow of fumes in this compartment, utilising a perforated metal plate in which the perforations are distributed in proportion with the rate of ow of the fumes passing through the various compartments.

A number of embodiments of the invention are illustrated by way of example in the accompanying drawings.

FIGURE l is a diagrammatic vertical section through a furnace provided with an apparatus according to the invention;

FIGURES 2 to 4 are horizontal sections along the line II-II of FIGURE 1, showing a number of constructional forms of the apparatus according to the invention;

FIGURE 5 is a horizontal sectional view taken along the line 5 5 of FIGURE 1; and

FIGURE 6 is a vertical sectional view looking along the line 6 6 of FIGURE 3 but showing a further modification of the invention.

Referring to FIGURE 1, the furnace denoted as a whole by the reference 1 is composed of an envelope 2 of refractory material forming the crucible 3 at the base and, above the latter, the exchanger column 4. There opens at the top of the exchanger column the orifice 5 for the charging of the furnace, provided with a hopper 6. Situated slightly below the orifice 5 is the orifice 7 through which the fumes emanating from the furnace are sucked and discharged to the stack. The raw materials forming the vitrifable batch are introduced into the furnace 1 through the hopper 6, fall in scattered form into the column 4 and collect in the crucible 3 where they are heated by burners as indicated in FIG. 1 to form a mass of molten glass 8.

Combustion gases are injected into the glass mass, which they heat, wherafter the gases rise through the column 4, thus heating the grains of batch, and escape through the orifice 7 to the stack.

In accordance with the invention, metallic elements 10 are disposed in the upper part 9 of the column 4. These elements may be of any shape and may be formed, for example, of chains or metal strips. Preferably, continuous elements are employed which form compartments or channels 11 open at their upper and lower ends,

but not intercommunicating. According to FIGURE 2, the elements are sheet-metal elements forming a chequerwork defining channels 11. According to FIG- URE 3, the sheet-metal elements divide the cross-section of the zone 9 into different sectors, of which there are eight in the illustrated arrangement. FIGURE 4 illustrates a partitioning formed of metal tubes 12. The passages 11 correspond to the interior of the tubes and the passages 11' to the intervals between the tubes. In the embodiment of FIGURE 6, the metallic elements are composed of intersecting transverse bars 10 dividing the cross-section of the zone 9 into sectors in the manner of the sheet metal elements illustrated in FIGURE 3 of the drawings, and a plurality of chains 10 depending from each of such transverse bars 10; the bars 10 and chains 10 forming sector-like channels such as the channels 11 illustrated in FIG. 3. The elements 10 are disposed in the column 4 below the orifice 7 for the discharge of the fumes and descend therein as far as is possible and compatible with their resistance to high temperature.

Referring again to FIGURE 1, the vitriable batch introduced into the furnace through the hopper 6 falls onto a perforated plate or screen 13 encased in a frame 14 resiliently supported by springs 15 to the envelope 2 of the furnace. The plate or screen 13 is vibrated by means not shown. The introducted batch spreads over the screen 13 which distributes it over the entire crosssection of the furnace. This distribution may be uniform or, if a perforated plate is provided, as is shown by the plate 13 in FIG. 5, it may be adjusted in accordance with an arbitrarily chosen law. For example, each channel 11 will be fed with a quantity of batch proportional to the rate of flow of flumes in the said channel. This is effected by perforating the plate 13 with a number of holes 13" proportional to the rate of ow of fumes.

Of course, the invention is not limited to the embodiments referred to by way of example, and modifications may be made thereto without departing from its scope.

We claim:

l. The method of preheating vitriliable matter to be converted into glass in a molten bath located at the bottom of a vertically disposed tubular furnace and from which hot fumes emanate as such matter is melted therein into a chamber rising directly up from the level of such bath through the lower half of the furnace and extending over the area of such tubular furnace, comprising causing said fumes to rise from said bath up toward the upper end of said furnace freely and straightly by initially causing the fumes to rise through said chamber in the lower half of the furnace as a single column having the same cross-sectional area as such lower half of the furnace, and then at the upper end of such chamber dividing said single column with partition means without reducing the overall cross-sectional area thereof except for the thickness of said partition means, to cause the fumes to rise from such lower furnace half directly up through a sectional area extending over the area of such Vtubular furnace and constituting the major portion of the upper half of the furnace and confining the divided fumes to cause them to rise as a plurality of freely moving, straight, vertically guided, unobstructed streams, supplying the particles of vitrifiable matter at the upper end of the furnace and causing such matter to fall freely through said sectional area as a plurality of vertically guided, unobstructed streams of such matter in countercurrent relation to the streams of hot fumes rising through said sectional area, converting a large portion of the heat in said rising fumes into radiant heat and subjecting each guided stream of vitriiiable matter to an enclosing envelope of such radiant heat throughout the vertical height of said sectional area, whereby the particles as they fall freely through the entire height of said sectional area and the lower half of the furnace are initially heated by `simultaneously subjecting the same to said vertical i envelopes of radiant heat and the heat in the rising streams of hot fumes, and are then heated by the high heat contained in the single column of hot fumes in said chamber directly below said sectional area and rising directly from the bath.

2. The method defined in claim 1 in which the streams of fumes pass through said sectional area at different rates of flow, and in which the particles of matter are distributed over the upper end of the furnace above such sectional area so that the amount thereof moving down in each stream thereof is proportionate to the rate of ow of the hot fume stream through which such particle stream flows in countercurrent relation.

3. A glass melting furnace comprising a vertically disposed tubular furnace having at the bottom thereof a Crucible in which the vitrifiable matter is melted with the emanation of hot fumes therefrom, and having a chamber rising directly up from the level of the molten bath of vitrifiable matter in said Crucible and extending over the area of said tubular furnace, said hot fumes rising freely, vertically and s-traightly from such molten bath up through such chamber and toward the upper end of said tubular furnace to be discharged at the upper end of the latter, perheating means located within said furnace in given spaced relation above said bath of molten materials and in the path of flow of said hot fumes, said preheating means being directly connected to the upper end of said chamber and being composed of a plurality of heat exchange elements of large surface area and constituted of material which is capable of readily absorbing heat from said hot fumes and transmitting such absorbed heat by radiation to the vitriable matter to be melted, said heat exchange elements of said preheating means subdividing the transverse interior area of said tubular furnace without reducing the overall cross-sectional area thereof except for the thickness of said heat exchange elements, for given vertical distance to provide a pularity of straight vertical, adjoining passageways extending continuously from the juncture of the lower end of said preheating means with the upper end of said chamber to the upper end of said preheating means and subdividing the single column of hot fumes rising up through said chamber from said bath into a plurality of adjoining streams of freely upwardly moving hot fumes having an overall cross-sectional area substantially the same as the Yarea of said tubular furnace and being vertically guided in their unobstructed movement by said passageways, and means at the upper end of said tubular furnace surmounting said preheating means for distributing particles of vitriable matter for the bath over the upper end of said preheating means in a given manner to provide in the vertical passageways of said preheating means, vertically guided streams of freely falling particles each flowing in countercurrent relation in one of such passageways to a divided stream of freely rising hot fumes, whereby the freely falling particles in the guided streams thereof as the latter ow down through the entire height of said preheating means, are subjected throughout the height of such preheating means to an enclosing envelope of heat radiated from said heat exchange elements and to heat conductively applied to such particles by the divided streams of hot fumes moving counterflow to such particle streams, said particles as they fall lfreely through the single column of hot fumes in said chamber directly below said preheating means to said bath being subjected to the high heat issuing and rising directly from said bath.

4. A glass furnace such as defined in claim 3, in whichA 5 6 tically disposed relation in said sectional area and ar- 2,658,743 11/53 Speil et a1. 263-10 ranged to form said vertically disposed continuous pas- 2,668,041 2/54 Knibbs 263-30 X sages. 2,722,733 11/55 Meyer et a1. 165-179 X 2,731,709 1/56 Gaddis et a1 165-179 X References Cited by the Examiner 5 2,958,151 11/60 Palmer 263-29 X UNITED STATES PATENTS j 538,225 4/95 Williamson u 263-30 X CHARLES SUIxALO, Plzmmy Examzner. 733,903 2/05 Skoog 263 30 PERCY L. PATRICK, Examiner. 2,470,543 5/49 Azbe 263-29 

1. THE METHOD OF PREHEATING VITRIFIABLE MATTER TO BE CONVERTED INTO GLASS IN A MOLTEN BATH LOCATED AT THE BOTTOM OF A VERTICALLY DISPOSED TUBULAR FURNACE AND FROM WHICH HOT FUMES EMANATE AS SUCH MATTER IS MELTED THEREIN INTO A CHAMBER RISING DIRECTLY UP THE LEVEL OF SUCH BATH THROUGH THE LOWER HALF OF THE FURNACE AND EXTENDING OVER THE AREA OF SUCH TUBULAR FURNACE, COMPRISING CAUSING SAID FUMES TO RISE FROM SAID BATH UP TOWARD THE UPPER END OF SAID FURNACE FREELY AND STRAIGHTLY BY INITIALLY CAUSING THE FUMES TO RISE THROUGH SAID CHAMBER IN THE LOWER HALF OF THE FURNACE AS A SINGLE COLUMN HAVING THE SAME CROSS-SECTIONAL AREA AS SUCH LOWER HALF OF THE FURNACE, AND THE AT THE UPPER END OF SUCH CHAMBER DIVIDING SAID SINGLE COLUMN WITH PARTITION MEANS WITHOUT REDUCING THE OVERALL CROSS-SECTIONAL AREA THEREOF EXCEPT FOR THE THICKNES OF SAID PARTITION MEANS, TO CAUSE THE FUMES TO RISE FROM SUCH LOWER FURNACE HALF DIRECTLY UP THROUGH A SECTIONAL AREA EXTENDING OVER THE AREA OF SUCH TUBULAR FURNACE AND CONSITUTING THE MAJOR PORTION OF THE UPPER HALF OF THE FURNACE AND CONFINING THE DIVIDED FUMES TO CAUSE THEM TO RISE AS A PLURALITY OF FREELY MOVING, STRAIGHT, VERTICAL GUIDED, UNOBSTRUCTED STREAMS, SUPPLYING THE PARTICLES OF VITRIFIABLE MATTER AT THE UPPER END OF THE FURNACE AND CAUSING SUCH MATTER TO FALL FREELY THROUGH SAID SECTIONAL AREA AS A PLURALITY OF VERTICALLY GUIDED, UNOBSTRUCTED STREAMS OF SUCH MATTER IN COUNTERCURRENT RELATION TO THE STREAMS OF HOT FUMES RISING THROUGH SAID SECTIONAL AREA, CONVERTING A LARGE PORTION OF THE HEAT IN SAID RISING FUMES INTO RADIANT HEAT AND SUBJECTING EACH GUIDED STREAM STREAM OF VITRIFIABLE MATTER TO AN ENCLOSING ENVELOPE OF SUCH RADAINT HEAT THROUGHOUT THE VERTICAL HEIGHT OF SAID SECTIONAL AREA, WHEREBY THE PARTICLES AS THEY FALL FREELY THROUGH THE ENTIRE HEIGHT OF SAID SECTIONAL AREA AND THE LOWER HALF OF THE FURNACE ARE INITIALLY HEATED BY SIMULTANEOUSLY SUBJECTING THE SAME TO SAID VERTICAL ENVELOPES OF RADIANT HEAT AND THE HEAT IN THE RISING STREAMS OF HOT FUMES, AND ARE THEN HEATED BY THE HIGH HEAT CONTAINED IN THE SINGLE COLUMN OF HOT FUMES IN SAID CHAMBER DIRECTLY BELOW SAID SECTIONAL AREA AND RISING DIRECTLY FROM THE BATH. 